Figure 6.

(A) ROS fluorescent units (FU) were determined over time in normal, cirrhotic, and normal-H₂O₂-converted hepatocytes. Normal hepatocytes (open circles) have a low basal level of ROS activity whereas cirrhotic hepatocytes (black diamonds) have a high steady-state level of ROS activity. Normal hepatocytes exposed to 10 μM H₂O₂ for 10 minutes (black triangles) failed to maintain a sustained ROS response. However, normal hepatocytes exposed to 10 μM H₂O₂ for 20 minutes (black squares) demonstrate sustained increased ROS activity similar to basal cirrhotic hepatocytes over the study period. These hepatocytes had 97% viability (data not shown). (B) The percent of condensed nuclei was determined in normal and H₂O₂-converted hepatocytes at 48 hours after pretreatment (or not) with trolox (2 μM) followed by treatment with or without TGFβ (5 ng/ml). Treatment with H₂O₂ alone did not increase apoptosis, and, similar to cirrhotic hepatocytes, H₂O₂-converted cells were resistant to TGFβ -induced apoptosis at 48 hours. However, H₂O₂-converted hepatocytes that were pretreated with trolox prior to TGFβ exposure underwent apoptosis similar to normal hepatocyte controls and antioxidant-treated cirrhotic hepatocytes.